Photographic supersensitized silver halide emulsions



United States Patent Int. (:1. misc 1/28 US. Cl. 96-104 4 Claims ABSTRACT OF THE DISCLOSURE A super-sensitized photographic silver halide emulsion containing at least one optical sensitizer represented by general Formula I below and at least one optical sensitizer represented by general Formula II below.

The individual moieties above are defined in the claims.

The present invention relates to a photographic silver halide sensitized by the combination of two types of optical sensitizers and more particularly to an opticalsensitized red-sensitive emulsion of light-sensitive color elements.

A multiple layer, light-sensitive color element, of the subtractive color processing type, usually comprises at least a blue-sensitive emulsion layer, a green-sensitive emulsion layer, and a red-sensitive emulsion layer. For obtaining good color reproduction with such a light-sensitive color element, the sensitizing ranges of the three layers must be sufficiently separated. Also, for this purpose, a red-sensitive emulsion layer having low green sensitivity, but high red sensitivity, is required. Further, the optical sensitizer used in the red-sensitive emulsion layer must not be diffused from said layer into other layers to give red sensitivity to the diffused layers. To obtain a high-sensitive color element, such an optical sensitizing method is required that gives high optical sensitization and is not accompanied by a reduction in optical sensitization owing to the presence of a coupler in the opticalsensitized light-sensitive emulsion layer and by a reduction in sensitivity with the lapse of time. The objects of this invention are to fulfill the above requirements.

The inventors have found that by using simultaneously the two types of the optical sensitizers shown below, the above objects of this invention can be successfully accomplished and in this manner an excellent red sensitivity can be obtained by a super-sensitization effect.

The photographic light-sensitive silver halide emulsion of the present invention is optically-sensitized by at least one optical sensitizer represented by the following general formula, Formula I, and at least oneoptical sensitizer represented by the following general formula, Formula II,

3,522,052 Patented July 28, 1970 Formula I 1 11 1 12 (X )nl and FormulaII S C2H5 S\ O-CH=(J3CH==C l l (X )n1 wherein R R R and R each represents a lower alkyl group, a substituted alkyl group, an allyl group, an

aralkyl group or a substituted aralkyl group, but, at least one of said groups R R R and R is a carboxyalkyl group or the derivative thereof, or a sulfoalkyl group or the derivative thereof; V represents a halogen atom, X- represents an anion, or the derivative thereof; V represents a halogen atom, and n is l or 2.

Illustrative of suitable substituted alkyl groups, fi-hydroxyethyl, ,B-acetoxyethyl, 'y-acetoxypropyl, ethylsulfate, propylsulfate, and the like, or carboxyalkyl, derivatives of a carboxyalkyl, sulfoalkyl, and derivatives of sulfoalkyl that have been defined above as being at least one of said groups R R R and R As the carboxyalkyl group or derivative thereof, suitable groups are, for example, carboxymethyl, S-carboxyethyl, -carboxypropyl, 2-(2-carboxyethoxy)-ethyl and the like. As the sulfoalkyl group or derivative thereof, suitable groups are, for example, fi-sulfobutyl, y-sulfopropyl, 6-sulfomethyl, 2-hydroxy-l-sulfopropyl, 3-methoxy 2 (3-sulfopropoxy)propyl, 2[2(3-sulfopropoxy)ethoxy]ethyl and 2-hydroxy-3- (3 -sulfopropoxy) propyl.

The optical sensitizer shown by general Formula I has been known as a panchromatic optical sensitizer. In particular, if a sulfoalkyl group or a carboxyalkyl group is introduced into at least one of group R and group R the reduction in optical sensitization caused by the pres ence of a coupler can be reduced. However, in the case of using the optical sensitizer there are certain drawbacks such that the extent of the improvement of the optical sensitivity by improving the reduction of optical sensitization is too little to accomplish the objects of the present invention, and the diffusion of the optical sensitizer into other layers is promoted by the reduction in the adsorption power for silver halides together with an increase in the hydrophilic property.

The optical sensitizer represented by general Formula II, that is, B-naphthothiacarbocyaniue has a longer color sensitive wave length range than that of the optical sensitizer represented by general Formula I, which is not desirable for color reproduction.

The inventors have found, however, that by using optical sensitizer I together with optical sensitizer II, they exhibit a very remarkable color sensitizing function and, hence, an extremely high color sensitization can be obtained. That is, by incorporating in a silver halide lightsensitive emulsion both optical sensitizer I and optical sensitzer II, there is exhibited a marked increase in red sensitization and a maximum optical sensitizing wave length in an intermediate range between those obtained in the cases of using the optical sensitizers individually. This makes it possible to change desirably the sensitivity distribution of the maximum optical sensitizing wave length range by changing the ratio of both color sensitizers.

The ratio of the proportion of optical sensitizer I to (PD) the proportion of optical sensitizer II in this invention has S S no specific limitation and may be suitably varied in a range 1,, of 9:1 to 1:9 according to the purpose. Further, the use of two such optical sensitizers that have not a sulfoalkyl group, a derivative of the sulfoalkyl group, a carboxylalkyl group or a derivative of the carboxyalkyl group in any of groups R R R and R said optical sensitizers S C E I 5 C-GH: -CH=C o1 \N or 02H I5 oH2dHi-s03 CH2(|3H2S03HN C2H5 C2115 not being included among the optical sensitizers of the (ILA) S s invention, results in a weak super-optical sensitization. 0211a The sensitization is too weak and the green sensitivity is I considerably increased with the increase in red sensitivity J by the addition of these sensitizers. This makes the use of N such optical sensitizers undesirable for the objects of this I I I invention (Cf. Example 1). The super-optical sensitiza- CH3 tion by the use of optical sensitizer I and optical sensi- 3- tizer II, according to the present invention, has great (1H3) merit in that the green sensitivity is not increased as coms S pared with the remarkable increase in red sensitivity. Fur- C2H5 there, it is also an important feature of the present invention that the dilfusion of optical sensitizers, from the emulsion layer containing them into other emulsion N layers, is prevented, as compared with the case of incor- I I I porating in the layer optical sensitizer I or optical sensi- E tizer II. Moreover, the reduction in red sensitivity which S03 is liabale to occur during preservation in a sensitizer-con- (IN?) S S taining emulsion layer of a light-sensitive color element Q2115 is decreased. The super-Optical sensitization achieved by the present invention is scarcely disturbed by coexistence in a silver 40 halide emulsion with a compound having an acid group, I: such as, a sulfonic acid group or a carboxyl group, for (911% Hm example, a surface active agent, a high molecular sensis03- ttiizer or a flocculat ng agent. Furthermore, by the addrsoaHNwzHm on of pseudocyanme, oxacarbocyamne, or 1m1dacarbocyanine in the silver halide emulsion containing the two optical sensitizers, according to the present invention, a The Present invention will now be further explained in highly sensitive super-panchromatic optical sensitivity can detail l in PracfiCe y referring to the following be obtained. eXamP e31 Examples of typical optical sensitizers used in this invention are illustrated below, although the optical sen- EXAMPLE 1 sitizers of this invention are not limited to them: Into 100 g. of a gelatino bromo-iodide emulsion (AgI (LA) S S 6.0 mol percent), which had been prepared by a conven- 2EE tional method, there (was added a i mol methanol solution of optical sensitizer I-A or optical sensitizer II-A, C1 1 or there were added a mol methanol solution of N N M optical sensitizer I-A and a mol methanol solution of (CIHO)3 L optical sensitizer II-A in the amount or amounts shown z below in Table 1. Thereafter, the system was stirred for S a minutes at 40 C. to stabilize the optical sensitization (H3) 3 s 60 action. Then, after adding a hardening agent, the emulsion |C2H6 was immediately applied to a film support and dried to provide a red-sensitive color element of the type to be 01 developed in a developer container coupler.

N The resulting film was cut into strips. The strips were ((llflm (IDECHZOH sub ected to red exposure through Fuji Filter No. 75 and A then to green exposure through Fuji Filter No. 17 by OOH means of a sensitometer at a color temperature of 4800 S o H K., and thereafter were developed in a primary black 2 5 and white developer having the following composition for color development.

\ f Black and white developer:

Metol-4 g. I (CHDS Sodium sulfite50 g. sol SOfiH-NOBHE Hydroquinone5 g.

Black and white developer (continued):

Sodium carbonate ;(mono-hydrate)40 g. Potassium bromide-- g.

Potassium thiocyanate1.0 g. Potassium iodide (0.1 )5 ml.

20 ml. of a 5% aqueous alkaline solution of the cyan coupler, represented by the following formula, was added with stirring:

Cyan coupler:

Water to make 1 liter (pH: 102:0.1 5 Development was followed by fixing to provide a black and white negative image. By measuring the densities of the thus obtained images, the relative red sensitivity and green sensitivity were ob- 10 sOflNa tained. The results are shown inTable 1. The system was neutralized by the addition of citric acid. After the addition of a hardening agent, the result- TABLE 1 mg emulsion was rmmedlately applied on a film base fi gfi 2;; gg and dried to provide a red-sensitive color film. methanol soln. methanol soln. ensisensi- The C0101 film was cut into Strips and y were of PA of (1111-) tivity 111! jected to red exposure through Fuji Filter No. 75 and to 2 0 100 652 green exposure through Fuji Filter N0. 17 by means of 5 g 128 23% a sensitometer at a color temperature of 3200 K. The 4:: 0 4 26:5 175 684 thus exposed color film was then color-developed for 2 2 675 20 minutes at 10 C. in a color developer having the followmu=Maximum sensitization wave length. i g COmP SitiOHZ As control data, the results similarly using the compara- C0101 develppefi G- tive optical sensitizers having the following formulas are N,1{'-d1ethY1am1I1-Para-acinoanlline Sulfate shown below in Table 2. 25 Sodmm Sulfite Sodium carbonate (monohydrate) 50.0 if. Water to make 1 liter (pH:10.8i0.1.

C CH= CH=C 30 The thus develped color film was subjected to primary C1 c1 fixing, bleaching and secondary fixing to provide a cyan N N negative image. The density of the thus obtained image (132E (IIZH5 was measured and the relative sensitivity and green sensitivity were calculated from the measured value, the results s C H s of which are shown in Table 3:

2 5 oon= zon=o Br- TABLE 3 5555 52; transit sts us I I methanol soln. methanol solu. sensisensi- C2H5 02115 N 0 0f o 11-0 (1111.) tivity tivity 13111.

1 2 0 24 100 652 2 4 0 29 115 652 3 o 2 31 210 686 4- 0 4 55 245 686 TABLE 2 2 1 355 672 Amount of Amount oi Relative Relative mu= a sen at o a e t h i sgl ii metl i n s l s r i si ser i No oi ii (mt') oi e mi. tivity tivity mp EXAMPLE 3 4 0 25 100 652 Into 100 g. of a gelatino bromo-iodide emulsion (AgI 7 0 4 20 74 675 5 20 mol percent), prepared by a conventional method, 8.---- 2 2 32 130 668 there was added a V1000 mol methanol solution of optical mu=Maximum sensitization wave length. sensitizer I-B or dI-B, or there were added a mol methanol solution of optical sensitizer I-B and a o From the results shown in Table 2, it will be understood mol mQthaHOI Solutio? of Optical sensitizer in the that when control optical sensitizers (F) and (G) were 55 P P P PQ shown in Table The System used containing neither a carboxyalkyl group nor a was .SFuTe-d for mlnutes at 40 C. to Stabilize the Optical sulfoalkyl group in any of groups R R R and R4 sensitization action. Apart from this, 5 g. ofacyan coupler similar to the optical sensitizers of this invention, the hall/111g the formula! increase of the red sensitivity by the super-sensitization was comparatively low and the green sensitivity was con- OH sidered increased. On the other hand, as described in I Table 1, when optical sensitizer I and optical sensitizer CONHCmHa; II of this invention were used simultaneously, the red sensitivity was increased remarkably while the increase of the green sensitivity was comparatively low.

EXAMPLE was dissolved in 10 ml. of dibutyl phthalate and the Into 100 g. of a gelatino bromo-iodide emulsion (AgI solution was dispersed in 1 00 g. of a 10% gelatino solu- 4.0 mol percent), there was added a 5 mol methanol tion, using 2 ml. of an aqueous 10% solution of sodium Solution of Optical sensitizer r r there were alkyl benzene sulfonate. Thereafter, '20 g. of the thus obadded both a 5. mol methanol solution of optical-sensitained coupler dispersion was dispersed in the abovetizer I-C and a V1000 mol methanol solution of optical senprepared emulsion. The resulting dispersion was, after the sitizer II-C, in the proportion or proportions as shown in addition of a hardening agent, applied to a film support Table 3. The system was stirred for 60 minutes at 40 C. and dried to provide a light sensitive color element of the to stabilize the optical sensitization action. Thereafter, type containing a coupler therein.

TABLE 4 Amount of Amount of Relative Relative 1/1,000 mol 1/1,000 mol green red methanol soln. methanol soln. sensisensi- N o of I-B (ml) of 11-13 (ml) tivity tivity mp.

1 m 11.: Maximum sensitization wave length.

EXAMPLE 4 Into 100 g. of a bromo-iodide emulsion (AgI 7.0 mol percent), prepared by a conventional method, there was dissolved a mol methanol solution of optical sensitizer LB or II-C, or there were dissolved a mol methanol solution of optical sensitizer I-D and a $1 mol methanol solution of optical sensitizer II-C in the amount or amounts shown on Table 5. The system was stirred for 30 minutes at 35 C. to stabilize the optical sensitization action and then applied to a film support followed by drying to provide a light-sensitive black and White element.

The film was cut into strips and they were subjected to yellow exposure through Fuji Filter No. 3 by means of a sensitometer at a color temperature of 2666 K. The thus exposed films were developed for 20 minutes at 20 C. in a D-76 (Eastman Kodak Co.) developer and then fixed to provide black and white negative images.

By measuring the densities of the negative images, the relative optical sensitizations were calculated. The results are shown in Table 5.

l M =Maximum sensitization wave length.

What is claimed is:

1. A photographic silver halide emulsion containing at least one optical sensitizer represented by the following general Formula I and at least one optical sensitizer represented by the following general Formula H and Formula II c H 2 5 I OGH=A OH=C wherein R R R and R each represents an alkyl group having 1 to 4 carbon atoms, a substituted alkyl group selected from the class consisting of hydroxyalkyl group, an acetoxyalkyl group, an alkylsulfate group, a carboXyalkyl group, a sulfoalkyl group, a carboxyalkoxyalkyl group, a hydroxysulfoalkyl group, an alkoxy sulfonalkoxy alkyl group, a sulfoalkoxy alkoxy alkyl group or a hydroxy sufoalkoxy alkyl group, an allyl group, an aralkyl group or a sulfo substituted aralkyl group, V represents a halogen atom; X- represents an anion; and n is 1 or 2.

2. The photographic silver halide emulsion of claim 1 wherein said optical sensitizers of Formulas I and II are present in the emulsion in a ratio by weight in the range of from 9:1 to 1:9.

3. The photographic silver halide emulsion of claim 1 wherein the sensitizer of Formula I is a compound selected from the group consisting of o1 f omoHQ-sm- CHzCHrSO3HN CzH5 and the sensitizer of Formula II is a compound selected from the group consisting of 4. A photographic light-sensitive element comprising as a component the halide emulsion as claimed in claim 1.

References Cited 

